Gateway radio frequency identification tag system

ABSTRACT

A system and method are disclosed for transporting deterministic traffic in a gigabit passive optical network. A system that incorporates teachings of the present disclosure may include, for example, an Optical Line Termination (OLT) for exchanging data traffic in a Gigabit Passive Optical Network (GPON) having a controller programmed to generate a timeslot schedule for transport of a desired bandwidth of constant bit rate (CBR) data traffic by selecting one or more timeslots from periodic frame clusters operating according to a GPON Transmission Convergence (GTC) protocol. Additional embodiments are disclosed.

This application is a continuation of U.S. Ser. No. 11/999,398, filedDec. 5, 2007, which is currently allowed and is herein incorporated byreference in its entirety.

FIELD OF THE INVENTION

This invention relates to a radio frequency identification (RFID)systems that use RFID tags to track product inventory, or other mobileitems.

BACKGROUND OF THE INVENTION

Information management systems are being developed to track the locationand/or status of a large variety of mobile entities such as products,vehicles, people, animals, etc. A widely used tracking technology usesso-called RFID tags that are placed physically on the items beingtracked. Reference herein to “items” being tracked is intended toinclude the variety of entities just mentioned as well as, morecommonly, product inventories.

RFID tags may be active or passive. Active tags typically haveassociated power systems and can transmit data over modest distances.Passive systems lack internal power but derive transmitting signal powerfrom an incoming RF signal. However, transmitting distances with passiveRFID tags are very limited. To read a large number of RFID tags, spreadover a wide physical area, requires either a large number of RFIDreaders, or a reliable system of moving RFID readers. One proposedsolution to this problem is to use active RFID tags on the products.However, active tags are relatively costly. Although they lend morefunction to a tracking system, and transmit more effectively, passivetags are typically more cost effective where inventories being trackedare large.

What is needed is an improved system for RFID tracking where the scaleof the application exceeds the performance capability of conventionalRFID approaches.

STATEMENT OF THE INVENTION

We have developed a new architecture for RFID systems that is adapted toprocess large numbers of RFID tags and provide information about a largenumber of items. The system provides for multiple tag readers. The tagreaders are active and have both transmit and receive capability. Thesystem includes a new element called a gateway tag that receivesinformation about individual items from the multiple readers and thuscontains data on the entire inventory of items. This allows each of themultiple readers to access data for the entire inventory of items. Thegateway tag may interface with an information storage center that alsocontains data for the entire inventory of items.

BRIEF DESCRIPTION OF THE DRAWING

The invention may be better understood when considered in conjunctionwith the drawing in which:

FIG. 1 is a schematic view of a typical RFID tag system;

FIG. 2 is a representation of a passive RFID tag;

FIG. 3 is a representation of an active RFID reader;

FIG. 4 is a schematic view of the RFID tag system of the invention; and

FIG. 5 is a representation of a gateway RFID tag according to theinvention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic representation of a typical RFID system whereinthe RFID tag is shown at 11, the RFID reader at 12 and a centralinformation store at 13. A wide variety of implementations are used forthe function of tracking large numbers of items, many of which use thebasic elements shown in FIG. 1. Typically, the RFID tag 11 is a passivedevice attached to the item being tracked. The reader 12 is an activeRFID device that communicates with large numbers of passive RFID tags,and typically either stores data in the reader, and/or relays data to acentral database 13. The central database keeps data for all items inthe system. In many applications, for example, large retail outlets, theRFID readers are mobile devices that are moved around the vicinity ofthe RFID tags to record the RFID tag data. Mobility in this applicationis necessary since the transmission distance between the RFID tags andthe RFID readers is very limited, for example, tens of meters maximum,and typically less than 10 meters. The RFID readers are typicallypowered, which extends the range of transmission between the RFIDreaders and a remotely located receiver. That allows the option of usinga RFID reader to simply relay RFID tags to a central database. Moretypically, the reader reads the passive RFID and stores the informationlocally. This data may be downloaded to the central store periodically,by placing the reader in a docking device that is connected by wirelessor hardwired link to the central database. In the latter case, awireless link between the RFID reader and a remote receiver may or maynot be used.

A passive RFID tag is shown at 21 in FIG. 2. RFID tags are miniaturizedas much as practical to allow for the essential elements of asemiconductor IC chip 22, typically a CMOS chip, and an antenna 23. TheIC chip contains a memory, usually a read-only memory encoded with itemdata. The antenna is a serpentine metal conductor that receives smallamounts of power from the RFID reader by inductive coupling. When the ICchip is powered, it transmits item data back to the RFID reader viaantenna 23.

Passive RFID tag designs are available in many sizes and designs. Commoncharacteristics are a platform, an IC chip, and an antenna. Depending onthe application the platform may be glass, ceramic, epoxy, paper,cardboard, or any suitable plastic. An onboard power source is notincluded in a passive RFID tag. All power for the tag is derived from RFsignals in the vicinity of the tag. The tag responds to the reader usingRF backscatter, which basically reflects the carrier wave from thereader after encoding data on the carrier wave. Variables in thecommunication specification include the frequency of the carrier, thebit data rate, the method of encoding and any other parameters that maybe needed. ISO 18000 and EPCGlobal are the standards for this interface.The interface may also include an anti-collision protocol that allowsmore than one tag in the range of the reader to signal concurrently.There are many specific implementations of this, and these form no partof the invention.

A typical schematic for an RFID reader is shown in FIG. 3. The reader 31includes RF transceiver chip 32, microprocessor chip 33, and battery 34.The transceiver chip communicates through an attached antenna asindicated. These components allow the reader to not only receive datafrom the passive RFID tags, but to store and process the data andtransmit the data to another device or station. Since the reader ispowered, it can transmit data over significant distances, for example,100 to 3000 thousand feet.

A schematic of an RFID tag system according to the invention is shown inFIG. 4. The RFID tags are shown organized in groups A, B, and C. Thesegroups may represent different departments in a retail outlet, separatefloors or buildings in a warehouse complex, separate railroad cars orshipping containers, etc. In the arrangement shown, each groupcommunicates with an associated RFID reader 41, 42, and 43. It should beunderstood that this arrangement is shown by way of example only. Thereare many alternative configurations using RFID tags and readers. TheRFID readers communicate with gateway RFID tag 45. The link between theRFID readers and the gateway RFID tag may operate at a frequencydifferent than the frequency used in the link between the RFID readersand the passive RFID tags. The readers collectively provide data to thegateway RFID tag for all of the items in the system. This arrangementallows any reader in the system to access data on any item in the systemvia the gateway RFID tag. Since the transmission to and from the gatewayRFID tag to the RFID readers is powered, that link may be essentiallyany distance within the facility served by the RFID system. The gatewayRFID tag may be a standalone unit, or, as indicated in FIG. 4,interfaced via network 46 to a central database and memory store 47. Thenetwork may be a wireless network, or a wired network (land line).

A schematic of the gateway RFID tag 45 in FIG. 4 is shown in FIG. 5. Thegateway RFID tag is an active tag, with battery 54. It also has aprocessor 53, a large memory 56, and an RF transceiver 52. The gatewayRFID tag interfaces with each of the RFID readers as shown in FIG. 4,and may interface with a central database via a wireless or wirednetwork. The latter is an optional feature. The system may be designedwith a direct interface between the RFID readers and the centraldatabase, as described in conjunction with FIG. 1, and with a parallellink between the RFID readers and the gateway RFID tag. Adding a linkbetween the gateway RFID tag and the central database allows dataconsistency between the two to be verified. Both of these subsystemstypically contain data on all of the items being tracked by the system,i.e. universal system data. However, using an arrangement like thatshown in FIG. 4 allows the universal system data stored at the gatewayRFID tag to be different (typically less detailed) than the data storedat the central database.

For the purpose of defining terms used herein, a passive RFID tag meansa device containing at least an integrated circuit chip operating at agiven frequency and an antenna, but no onboard power source. The antennaoperates as a low power RF transceiver. The integrated circuit chipcontains a memory. An RFID reader means a device containing at least anintegrated circuit chip, an antenna, an RF transmitter, an RF receiver,and a power source. The integrated circuit chip in the RFID readercontains a memory. The RFID reader has an RF transmitter that operatesat the same frequency as the RFID tags, and an RF transmitter that mayoperate at a frequency different from that of the RFID tags. A gatewayRFID tag means a device containing at least an integrated circuit chip,an antenna, an RF transmitter, an RF receiver, and a power source. Theintegrated circuit chip in the gateway RFID reader contains a memory.The gateway RFID reader has an RF transmitter that operates at the samefrequency as the RFID readers, and may have a communications link to aremote central database. A remote central database has a microprocessorand a memory store. It may or may not be located on the same physicalpremises as the gateway RFID tag.

Transmitting range means the range over which signals transmitted from atransmitting device can be received by a receiving device.

In summary, an aspect of the invention is that data from an item that isnot in the vicinity of an RFID reader, and thus not accessible directlyfrom that reader, can nevertheless be accessed by that reader throughthe gateway RFID tag. The sequence of operations for accomplishing thisinvolves transmitting an RFID signal between a first RFID reader and afirst group of passive RFID tags, receiving at the first RFID readerfirst data from the first group of passive RFID tags, transmitting saidfirst data from the RFID reader to a gateway RFID tag, receiving andstoring the first data at the gateway RFID tag, transmitting an RFIDsignal between a second RFID reader and a second group of passive RFIDtags, receiving at the second RFID reader second data from the secondgroup of passive RFID tags, transmitting said second data from the RFIDreader to the gateway RFID tag, receiving and storing the second data atthe gateway RFID tag, transmitting to the gateway RFID tag a query fromthe first RFID reader, receiving the query at the gateway RFID tag, andtransmitting second data from the gateway RFID tag to the first RFIDreader.

Various additional modifications of this invention will occur to thoseskilled in the art. All deviations from the specific teachings of thisspecification that basically rely on the principles and theirequivalents through which the art has been advanced are properlyconsidered within the scope of the invention as described and claimed.

1. A method for radio frequency identification tracking, comprising:transmitting a first radio frequency identification signal by a firstradio frequency identification reader to a first group of passive radiofrequency identification tags; receiving at the first radio frequencyidentification reader first data from the first group of passive radiofrequency identification tags in response to the first radio frequencyidentification signal; transmitting the first data by the first radiofrequency identification reader to a gateway radio frequencyidentification tag; transmitting a query by the first radio frequencyidentification reader requesting second data from the gateway radiofrequency identification tag, wherein the second data was previouslytransmitted to the gateway radio frequency identification tag by asecond radio frequency identification reader; and receiving the seconddata from the gateway radio frequency identification tag by the firstradio frequency identification reader.
 2. The method of claim 1, whereinthe second data comprises a response from a second group of passiveradio frequency identification tags responding to a second radiofrequency identification signal from the second radio frequencyidentification reader.
 3. The method of claim 1, wherein the first dataand the second data are transmitted by the gateway radio frequencyidentification tag to a central database.
 4. The method of claim 1,wherein the first data is received from the first group of passive radiofrequency identification tags by the first radio frequencyidentification reader at a first radio frequency, and the first data istransmitted by the first radio frequency identification reader to thegateway radio frequency identification tag at a second radio frequency.5. The method of claim 4, wherein the query is transmitted at the secondradio frequency.
 6. The method of claim 3, wherein the first data andthe second data are transmitted from the gateway radio frequencyidentification tag to the central database via a wireless network. 7.The method of claim 3, wherein the first data and the second data aretransmitted from the gateway radio frequency identification tag to thecentral database via a wired network.
 8. The method of claim 1, whereinthe gateway radio frequency identification tag comprises an integratedcircuit chip, a radio frequency transmitter, a radio frequency receiver,a power supply, and a radio frequency antenna.
 9. The method of claim 1,wherein the first data and second data are stored at the gateway radiofrequency identification tag.
 10. A radio frequency identificationtracking system comprising: a first passive radio frequencyidentification tag; a gateway radio frequency identification tag; afirst radio frequency identification reader comprising: a first radiofrequency transmitter for transmitting a first radio frequency signal tothe first passive radio frequency identification tag; a first radiofrequency receiver for receiving first tag data from the first passiveradio frequency identification tag in response to the first radiofrequency signal; and wherein the first radio frequency transmitter isfor transmitting the first tag data from the first passive radiofrequency identification tag to the gateway radio frequencyidentification tag, and for transmitting a first query from the firstradio frequency identification reader to the gateway radio frequencyidentification tag, wherein the first query comprises a first requestfor second data from the gateway radio frequency identification tag,wherein the second data was previously transmitted to the gateway radiofrequency identification tag by a second radio frequency identificationreader.
 11. The radio frequency identification tracking system of claim10, further comprising: a second passive radio frequency identificationtag; the second radio frequency identification reader comprising: asecond radio frequency transmitter for transmitting a second radiofrequency signal to the second passive radio frequency identificationtag; a second radio frequency receiver for receiving second tag datafrom the second passive radio frequency identification tag in responseto the second radio frequency signal; and wherein the second radiofrequency transmitter is for transmitting the second tag data from thesecond passive radio frequency identification tag to the gateway radiofrequency identification tag, and for transmitting a second query fromthe second radio frequency identification reader to the gateway radiofrequency identification tag, wherein the second query comprises asecond request for the first tag data from the gateway radio frequencyidentification tag.
 12. The radio frequency identification trackingsystem of claim 11, wherein the gateway radio frequency identificationtag comprising: a third radio frequency receiver for receiving the firsttag data, second tag data, the first query, and the second query fromthe first radio frequency identification reader and the second radiofrequency identification reader; a memory for storing the first tag datafrom the first radio frequency identification reader and the second tagdata from the second radio frequency identification reader; and a thirdradio frequency transmitter for transmitting to the first radiofrequency identification reader, in response to the first query from thefirst radio frequency identification reader, the second tag datareceived from the second radio frequency identification reader, andtransmitting to the second radio frequency identification reader, inresponse to the second query from the second radio frequencyidentification reader, the first tag data received from the first radiofrequency identification reader.
 13. The radio frequency identificationtracking system of claim 10, further comprising: a central databaseconnected to the gateway radio frequency identification tag via anetwork.
 14. The radio frequency identification tracking system of claim10, wherein the first radio frequency transmitter for transmitting thefirst radio frequency signal to the first passive radio frequencyidentification tag operates at a first radio frequency, and the firstradio frequency transmitter for transmitting the first tag data from thefirst radio frequency identification reader to the gateway radiofrequency identification tag operates at a second radio frequency. 15.The radio frequency identification tracking system of claim 14, whereinthe first radio frequency transmitter transmits the first query to thegateway radio frequency identification tag using the second radiofrequency.
 16. The radio frequency identification tracking system ofclaim 13, wherein the network is a wireless network.
 17. The radiofrequency identification tracking system of claim 13, wherein thenetwork is a wired network.
 18. A method for radio frequencyidentification tracking, comprising: receiving first data by a gatewayradio frequency identification tag from a first radio frequencyidentification reader, wherein the first data comprises a first responsefrom a first group of passive radio frequency identification tagsresponding to a first radio frequency identification signal from thefirst radio frequency identification reader; receiving second data bythe gateway radio frequency identification tag from a second radiofrequency identification reader, wherein the second data comprises asecond response from a second group of passive radio frequencyidentification tags responding to a second radio frequencyidentification signal from the second radio frequency identificationreader; receiving a first request from the first radio frequencyidentification reader for the second data; and transmitting the seconddata to the first radio frequency identification reader.
 19. The methodof claim 18, further comprising: receiving a second request from thesecond radio frequency identification reader for the first data; andtransmitting the first data to the second radio frequency identificationreader.
 20. The method of claim 18, further comprising: transmitting bygateway radio frequency identification tag the first data and the seconddata to a central database.